Unresolved target detection improvement by use of multiple matched filters approach at different spatial phases

• US 20070036439A1
• Filed: 03/31/2005
• Published: 02/15/2007
• Est. Priority Date: 03/31/2005
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Chen, Hai-Wen
• Granted Patent: US 7,362,880 B2
• Time in Patent Office: Days
• US Class Current: 382/209
• CPC Class Codes: G06F 18/253 of extracted features
• CPC Class Codes: G06T 2207/10048 Infrared image
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80
• CPC Class Codes: G06V 10/255 Detecting or recognising potential candidate objects based on visual cues, e.g. shapes
• CPC Class Codes: G06V 10/443 by matching or filtering
• CPC Class Codes: G06V 10/806 of extracted features

Abstract

A method and system for detecting a point source target using multiple matched filters are disclosed. A sensor, which is preferably an infrared focal plane array, includes a plurality of pixels for providing image data. A processor processes the image data from a selected pixel corresponding to a potential point source target and from a plurality of neighboring pixels. The system includes multiple filters having a plurality of different phases, including at least a center phase and four corner phases. The multiple filters filter the image data to obtain different filtered spatial images. A detector, which is preferably a CFAR detector, detects a target based upon the spatially filtered images from the multiple matched filters.

Claims

1. A method for detecting a point source target using multiple matched filters, comprising the steps of:

receiving image data from a sensor having a plurality of pixels;

processing the image data from a selected pixel corresponding to a potential point source target and from a plurality of pixels neighboring the selected pixel;

selecting a plurality of spatial filters having a plurality of different phases, including at least a center phase and four corner phases;

filtering the image data with the selected spatial filters to obtain different filtered spatial images; and

detecting a target based upon the filtered spatial images.

2. A method according to claim 1 wherein at least five spatial filters are selected.

3. A method according to claim 1 wherein at least nine spatial filters are selected.

4. A method according to claim 3 wherein the spatial filters include at least four edge phases.

5. A method according to claim 1 which further includes the step of normalizing the filtered image data by dividing the filtered image data with a background estimation.

6. A method according to claim 5 which further includes the step of averaging the filtered spatial images.

7. A method according to claim 6 which further includes the step of summing the intensities of the filtered spatial images.

8. A method according to claim 1 wherein the detecting step includes a constant false alarm rate detection.

9. A method according to claim 6 wherein the averaging includes an average of the four corner phasing filter outputs at different pixel locations.

10. A method according to claim 6 wherein the averaging includes an average of the four corner phasing filter outputs with at least a one pixel shift.

11. A method according to claim 1 wherein the detecting step includes a multiple thresholding technique.

22. A method according to claim 1 wherein a least square time-differencing process is applied to the image data prior to filtering.

12. A system for detecting a point source target using multiple matched filters, comprising the steps of:

a sensor having a plurality of pixels for providing image data;

a processor for processing the image data from a selected pixel corresponding to a potential point source target and from a plurality of pixels neighboring the selected pixel;

a plurality of spatial filters having a plurality of different phases, including at least a center phase and four corner phases, said spatial filters filtering the image data to obtain different filtered spatial images; and

a detector for detecting a target based upon the spatially filtered images.

13. A system according to claim 12 wherein at least five spatial filters are utilized.

14. A system according to claim 12 wherein at least nine spatial filters are utilized.

15. A method according to claim 12 wherein the spatial filters include at least four edge phases.

16. A system according to claim 12 wherein the filtered image data that is normalized with an estimator that divides the filtered image data with a background estimation.

17. A system according to claim 16 wherein the filtered spatial images are averaged.

18. A system according to claim 17 wherein the intensities of the filtered spatial images are summed.

19. A system according to claim 12 wherein the detector includes a constant false alarm rate detector.

20. A system according to claim 12 wherein the detector includes multiple thresholds.

21. A system according to claim 12 wherein the sensor includes an infrared focal plane array.